I would agree with your Mom, that sometime in the future you apologize, as in not now. But that time isn't until your W is open to reconciling. An apology isn't going to win her back when she just wants to get away, too little too late (will be the mindset).
However, if things turn around and she starts being open to the possibility, a well thought out, heartfelt apology can show that you recognize hurtful actions done in the past, and if someone at least recognizes it, then there is hope they won't repeat them.
No pressure, validating, just being a lighthouse is the way to help her find the way back to wanting to R. Maybe take some time to go back and read the validating and lighthouse threads in the newcomer welcome post that cadet put on your first page.
M - 9 1/2 years 5/5/16 - Bomb drop - 3 week EA 10/31/16 - We sold house 01/10/18 - D Finalized